1. Field of the Invention
The invention relates generally to magnetic recording hard disk drives (HDDs), and more particularly to an HDD that has multiple read amplifier/write driver integrated circuits connected to the system-on-a-chip (SOC) by a common transmission line.
2. Description of the Related Art
HDDs typically include a main integrated circuit, which is typically a system-on-a-chip (SOC) that contains many of the electronics and firmware for the HDD. The SOC is connected by a transmission line on a flex cable to the HDD's read amplifier/write driver integrated circuit (preamp IC). The preamp IC is typically located on the actuator that moves the read/write heads to the selected data tracks on the disks. The data to be written by the write head is sent from the SOC to the preamp IC, where the write driver generates analog write current pulses that are applied to the inductive coil in the write head to write data by selectively magnetizing the magnetic media of the recording layer on the disk. The data read back from the disk by the read head is transmitted from the preamp IC to the SOC.
The preamp IC includes multiple ports for controlling multiple heads, with each head accessing an associated disk surface. However, the demand for higher storage capacity per HDD requires an increase in the number of disks and heads, and thus an increase in the number of preamp IC ports to support those heads. Preamp ICs with high numbers of ports are available but at a significant cost increase. Therefore, utilizing multiple preamp ICs with a smaller number of ports would be advantageous from a cost perspective. The challenge is creating a disk drive with multiple preamp ICs connected to the SOC by a common transmission line and common digital logic control lines, and that operates seamlessly like a disk drive with a single preamp IC.